1. Field of the Invention
The invention relates to a roller bearing, for example, a cylindrical roller bearing, a tapered roller bearing or a convex roller bearing (spherical roller bearing). The invention relates to a roller bearing that is suitably used for rotatably supporting, for example, a rotating shaft in a gearbox for wind-power generation.
2. Description of Related Art
Japanese Patent Application Publication No. 2007-64434 (JP 2007-64434 A) describes a tapered roller bearing that is an example of a conventional roller bearing.
The tapered roller bearing includes an outer ring, an inner ring, a plurality of tapered rollers and a plurality of separators. The tapered rollers and the separators are arranged between the outer ring and the inner ring. The inner ring has a rib that is positioned next to a tapered raceway surface of the inner ring and at a large diameter-side end of the inner ring. The rib has a roller guide surface, and the roller guide surface guides a large diameter-side end surface of the tapered roller. In addition, a lubricant is supplied between the inner ring and the outer ring.
Each separator is arranged between the two tapered rollers that are next to each other in the circumferential direction of the tapered roller bearing. Each separator has a concave surface on which the tapered roller slides, and a groove. The groove extends in the axial direction, the radial direction or the circumferential direction of the tapered roller bearing.
In the tapered roller bearing described above, the separators are used instead of a cage conventionally used. Thus, the above-described tapered roller bearing includes a larger number of tapered rollers and therefore has a higher bearing load-carrying capacity. The lubricant stored in the groove is supplied to sliding portions such as a rolling contact surface of the tapered roller. Thus, for example, when the tapered roller bearing rotates at high speed under no-load conditions, it is possible to suppress smearing and seizure that may occur if the tapered rollers slip.
However, the conventional tapered roller bearing described above has a problem that the effect of suppressing smearing and seizure of the sliding portions is not sufficient. Especially, there is a problem that the effect of suppressing seizure of the roller guide surface is not produced.